Definitely do not carry it all in cash, ironic as that is to points being made about the dangers of a cashless society. Point being, a large amount of cash on anyone has for a long time been deemed suspect, and suspect to confiscation, often never to be seen again, or at least delayed return.
By the way, if you can plan your route north of 100 miles from the border, you can at least avoid the fucking Border Patrol that have amassed unconstitutional powers of forfeiture, search, seizure and arrest.
My dozens of encounters with Border Patrol have taught me to fear any such encounters. Won’t go into any stories, but I have a few very frightening ones.